Twenty-seven Magellanic penguins, Spheniscus magellanicus (Sphenisciformes), were collected from September 1996 to November 2000 from Península Valdés (42°04′–42°53′S; 63°38′–64°30′W), on the Patagonian coast, Argentina and the gastrointestinal tract was examined for helminths. All birds were parasitized by at least 1 of the 5 following parasite species: Tetrabothrius lutzi (Cestoda); Cardiocephaloides physalis (Lutz, 1926) (Digenea), Contracaecum pelagicum (Johnston and Mawson, 1942), Cosmocephalus obvelatus (Creplin, 1825) (Nematoda), and Corynosoma sp. (Acanthocephala). The total mean intensity was 686. The helminth community composition of S. magellanicus is reported for first time in Argentina increasing the host range of many of the species registered.